File(s) under permanent embargo

Reason: This item is currently closed access.

Census and typology of braided rivers in the French Alps

journal contribution
posted on 03.02.2017, 09:23 by Herve Piegay, Adrien Alber, Louise Slater, Laurent Bourdin
Following the implementation of the European Water Framework Directive (WFD) and the need to reach a “good ecological status” for rivers,key-questions are being raised about braided rivers. Before any environmental policy can be drawn up, these rivers need to be located, long term changes must be evaluated, and the regional diversity of such systems must be understood, as their inner complexity has not yet been well studied. Therefore, the aim of this work is to carry out a census of the braided channels of the French Alps and to establish a typology based on basic geomorphic indicators. A minimum estimate of the cumulative length of braided rivers prior to major infrastructure construction amounted to 1214 km. Around 53% of these rivers have disappeared during the last two centuries in relation to embankment or channelization, but a loss of 17% is still unexplained. The range in catchment size, mean slope and active channel width has been determined for the Western Alpine braided channels as well as the range in changes due to narrowing, widening and shifting. Seven types of braided rivers have been distinguished based on geographical settings (climate conditions and geology) and differences in terms of adjustment to human pressure on peak flow and sediment delivery. The percentage area of islands in the active channel and the relative length of banks also show a regional difference. Maximum and minimum thresholds of braided activity have been established taking into account the active channel width and the catchment area. The position of the studied reaches between these two thresholds are discussed in relation to position of rivers known in the literature, considering both long term trends and short-term fluctuations in channel width.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Aquatic Sciences

Volume

71

Issue

3

Pages

371 - 388

Citation

PIEGAY, H. ...et al., 2009. Census and typology of braided rivers in the French Alps. Aquatic Sciences, 71(3), pp. 371-388.

Publisher

© Birkhauser Verlag

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2009

Notes

This paper is in closed access.

ISSN

1015-1621

eISSN

1420-9055

Language

en

Exports